In the prior art, the damping characteristics of a hydraulic shock absorber used in an automobile differ depending on the type of vehicle. Consequently it is necessary to manufacture a plurality of types of piston assembly from a single type of piston main body by varying the valves or the like mounted on the piston main body or by varying the shape or number of orifices stamped in the piston main body.
A prior-art example of a method for manufacturing a piston assembly as shown in FIG. 4 comprises the sequence of a process of forming a piston main body by sintering, a process of stamping an orifice in the piston main body, a process of forming a molded sealing in the piston main body and a process of mounting a valve on the piston main body. A piston assembly manufactured in the above manner is then transported to the hydraulic shock absorber manufacturing step.
However in this type of prior-art hydraulic shock absorber manufacturing process, it is necessary to monitor inventory levels in the four manufacturing steps executing respective processes. Thus the problem arises that intermediate inventory availability must be increased. In particular, in the process after stamping the orifice into the piston main body, since a plurality of piston assembly types are produced as a result of the shape or the number of orifices, it is necessary to monitor a plurality of inventory levels in response to the piston assembly type. Consequently the problem arises that time is required to adapt to variations in the production level or to variations in product design.
It is therefore an object of this invention to provide a system for a method of manufacturing a hydraulic shock absorber which is characterized by high productivity.
It is a further object of this invention to provide a factory production system for a hydraulic shock absorber which is characterized by high productivity.